21998670 has 16 divisors (see below), whose sum is σ = 52796880. Its totient is φ = 5866304.

The previous prime is 21998659. The next prime is 21998677. The reversal of 21998670 is 7689912.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21998677) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 366615 + ... + 366674.

It is an arithmetic number, because the mean of its divisors is an integer number (3299805).

Almost surely, 2^21998670 is an apocalyptic number.

21998670 is an abundant number, since it is smaller than the sum of its proper divisors (30798210).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21998670 is a wasteful number, since it uses less digits than its factorization.

21998670 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733299.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 21998670 is about 4690.2739792042. The cubic root of 21998670 is about 280.1982864179.

It can be divided in two parts, 219 and 98670, that added together give a palindrome (98889).

The spelling of 21998670 in words is "twenty-one million, nine hundred ninety-eight thousand, six hundred seventy".